Endocardial Fibroelastosis

The endocardium of the right ventricle is thickened, white, and glistening.  EFE can be secondary to increased wall stress as in severe aortic stenosis or can be primary.

This trichrome stained section shows marked thickening of the endocardium with fibrosis. Strands of fibrous tissue extend into the myocardium.  EFE can be primary or secondary to increased wall stress as in aortic valve atresia or severe stenosis.  Primary EFE is now rare. It usually follows intrauterine viral myocarditis, especially mumps.

This elastic stain is of the thickened endocardium shows a marked increase in elastic fibers. Primary EFE is now rare.

Endocardial fibroelastosis (EFE) is characterized by diffuse thickening of the endocardium, predominantly in the ventricles. It can be secondary to abnormal wall stress as in aortic stenosis or it can be primary in infants and fetuses. Primary EFE can present as heart failure in infants or children or rarely as hydrops fetalis. Presenting symptoms include failure to thrive, dyspnea, excess sweating, or wheezing. Examination may show cardiomegaly, gallop rhythm, an apical systolic murmur consistent with mitral regurgitation, and signs of congestive failure. Familial cases have been reported with evidence for varying mendelian patterns of inheritance. The etiology of sporadic cases has not been definitively established but there is much evidence for a viral etiology. The incidence has been noted to increase after Coxsackie B epidemics and the disease has been produced in animal models by causing viral myocarditis. There has been a marked decrease in congenital EFE over the past few decades in parallel with the decrease in the prevalence of mumps associated with vaccination. PCR studies have shown the presence of the mumps viral genome in involved myocardium of patients with congenital EFE suggesting maternal transmission of the virus during pregnancy.